Waterbeds have become an increasingly popular type of bed. Waterbeds offer many advantages over conventional boxsprings and mattresses.
One such advantage is that a waterbed equally distributes pressure over a person's body, thereby eliminating the frequent discomfort caused by unequal pressure distributions in conventional boxspring and mattress beds.
Another reason why waterbeds have become popular is that the temperature of the mattress can be controlled. In a conventional bed, a person must rely on layers of blankets, turning up the heat in the building, or other means to stay comfortable during cold nights.
By contrast, a waterbed can enhance comfort by means of a water heater generally located underneath the water bladder and controlled by a thermostat. The heater heats the water inside of the water bladder to the desired temperature to make the bladder warmer than the ambient air, thereby making many layers of blankets unnecessary and allowing energy to be conserved by turning down the heat in the building.
Generally, the water heater is controlled only by a conventional thermostat, which has an "off" position, and variable temperature settings when turned on. However, applicant is unaware of any means whereby a waterbed heater may be prevented from activating in the event that there is insufficient water in the water bladder or if other dangerous conditions arise.
When the waterbed is initially installed, the heater is typically first placed on top of the bed frame and the water bladder placed on top of the heater. If the heater is inadvertently turned on before sufficient water is introduced into the water bladder, for example, or if a person forgets to turn the heater off after draining the bed, the temperature of the water heater or of the water in the bladder may rise to a dangerous level. If the melting point of the water bladder is reached, the bladder will be destroyed. If the ignition temperature of the surrounding wood frame or bed clothing such as sheets or blankets, or other surrounding material is reached, a fire may result. It is also possible that a person will inadvertently come into contact with the overheated bladder or water contained therein, and be burned. This danger is especially great to small children.
A dangerous condition may also arise where a person inadvertently places a blanket or sheet or other flammable material between the water heater and the water bladder. In such a case, it is possible that such material may catch fire.